When providing streaming multimedia telecommunication services, measuring audio quality experienced by a user while offering telecommunication services is indispensable for managing in-service quality and dealing with customer complaints. A method of most accurately measuring the QoE (Quality of Experience) is a subjective quality assessment method of assessing the QoE actually by a subject. However, this method cannot measure in-service quality. Thus, there is a demand for developing a technique of objectively measuring the QoE.
Objective quality assessment methods are classified into several categories. A parametric model is a model for estimating the QoE from inputted quality factors based on the relationship between the quality factors and the QoE. This model is suited to the service quality design. A parametric packet-layer model is a model for measuring, based on packet header information on the transmitting/receiving side, some of quality factors given as inputs of the parametric model. This model is suitable for measuring the in-service QoE. ITU-T (International Telecommunication Union Telecommunication Standardization Sector) recommendation P.564 defines a standard for a packet-layer model for a telephone-band or wideband telephone (see reference “Conformance testing for narrow-band voice over IP transmission quality assessment models”, ITU-T Recommendation P.564, July 2006”).